Animation of erupting volcanoes, lava flows and storms on the primordial Earth. The Moon is seen in the sky through the clouds. At this early stage, the Moon was far closer to Earth than it is now. During the Archaean Eon of the Earth's past, between 2.5-4 billion years ago, volcanic activity was much more pronounced, and the atmosphere lacked oxygen and was much richer in greenhouse gases. This kept the surface warm enough for some liquid water, despite the Sun only emitting some 70% of its current energy output. Despite these hellish conditions, life began on Earth during the Archaean Eon.